A related-art image funning apparatus, such as a laser printer, has a light scanning device that enables light from a light source to be incident onto a polygon mirror (polygonal rotating mirror) and scans reflected light thereof to expose a surface of a photosensitive member. As the light scanning device, there has been known a multi-beam scanning device that includes a light source having a plurality of light emitting points.
Additionally, there has been known a light scanning device that holds a light source configured by a semiconductor laser and a coupling lens for converting diffusion light from the light source into light flux with one holding member (JP-A No. 11-72729). The holding member is screw-engaged to a main body of the light scanning device by a screw and the like. Thereby, the light source and the coupling member are positioned with respect to an optical system of the main body of the light scanning device.
According to the above multi-beam scanning device, the light source is positioned as described in JP-A No. 11-72729. In other words, the light source is pressed in a holder and fixed to the holder by an adhesive. The holder having the light source fixed thereto is entirely rotation-adjusted with respect to an optical box having the polygon mirror. By the rotation-adjustment, a pitch between laser lights that are scanned to a photosensitive member from a plurality of light sources is adjusted at an appropriate interval.
According to the related art device, the rotation of the light sources is adjusted through the holder, which holds the light sources, so as to adjust the pitch of the light sources. However, according to this configuration, even when rotating the holder about a center of the light source serving as a rotational axis line, if there is a deviation (tolerance) between sizes of the pressed portions of the holder and the optical element, the rotational axis line is deviated during the adjustment. Thus, a direction of an optical axis of the laser light is changed or inclined. In other words, according to the conventional configuration, it is difficult to precisely adjust the pitch interval between the laser lights. Due to this, even when adjusting the rotation of the holder that holds the light sources, the pitch between the laser lights is not precisely adjusted. As a result, an exposure position on the photosensitive member is deviated from a normal position, which affects image quality.